Gas pressure actuators

ABSTRACT

A pressure actuator for a missile system comprising a slide valve member slidable within a bore under combustion chamber gas pressure to close safety vents and operate a percussion priming device to fire an ignition charge, the latter producing gas to actuate the missile system.

iiiie 91m Sindali 1451 Feb. 6, 1973 GAS PRESSURE ACTUATORS [75] Inventor: John Henry Sindall, Worcester, En- [56] References cued land UNITED STATES PATENTS Assigneer Imperial Metal Industries (Kylmh) 2,499,227 2 1950 Miles ..s9/1 B Limited, Warwichshire, England 2,939,393 6/1960 Johnson et a1 Filed: g 1971 3,106,131 10/1963 Barret a1. ..89/1B [21] Appi. No.: 172,115 Primary Examiner-Samuel W. Engie Att0rney-Cushman, Darby & Cushman {30] Foreign Application Priority Data [57] ABSTRACT Aug, 18, 1970 Great Britain ..39,733/70 A pressure actuator for a missile System comprising a slide valve member slidable within a bore under com [52] US. Cl. ..89/l R, 89/l.812, 102/49.7, bustion Chamber gas pressure to Close Safety vents and 102/70 R operate a percussion priming device to fire an ignition I Cl. v i g the latter producing g to actuate the missile [58] Field of Search ..60/26.1; 102/70, 49.3, 49.4,

system.

227/9, 10 -4 Claims, 3 Drawing Figures PATENTEDFEB 6 I975 3,714,863

SHEET 2 [IF 3 PATENTEDFEE s 1975 SHEET 30F 3 GAS PRESSURE ACTUATORS BACKGROUND OF THE INVENTION This invention relates to gas operated pressure actuators for missile systems.

When a rocket motor has been fired to propel a missile through the atmosphere, it is sometimes required to actuate an ancillary device of the missile. Examples of such ancillary devices are navigational aids, flares, flight guidance means and pumps, as well as other igniters required for instance to ignite ram jets.

Hitherto such ancillary devices have been initiated by gas igniters fired by electric fuseheads, or by gas pressure from the rocket motor, or by pressure actuators operated by pressurized fluid. However, the electric fuseheads are susceptible to interference by radar and other electric sources, and pressure-actuated devices utilizing the gas pressure from the rocket motor have to accept this at high temperature and pressure to operate the actuator (typically 2 cu. ins. at 4,000 C and l,500 p.s.i. to initiate ram jets).

It would therefore be desirable if a pressure actuator could be manufactured to operate with a volume of gas at lower temperature and pressure.

SUMMARY OF THE INVENTION According to present invention a pressure actuator for a missile system comprises a housing having a bore with an inlet port at a rear end thereof, an outlet port at the forward end thereof, and at least one outlet vent intermediate the inlet and outlet ports, a slide valve member slidably mounted within the bore but releasably retained adjacent the rear end of the bore by collapsible means interconnecting the housing and the valve member, the valve member having a forwardly facing striking surface and a forwardly extending sleeve portion which terminates rearwardly of the outlet vent but is adapted to close the outlet vent on forward movement of the valve member, the actuator further comprising a percussion-operated priming device mounted forwardly of, and axially aligned with, the striking surface of the valve member, and an ignition charge disposed forwardly of the priming device, the arrangement being such that upon operation of the actuator the slide valve member closes the outlet vent before the priming device is struck.

Preferably, the ignition charge is spaced from the priming device and is disposed intermediate the outlet vent and the outlet port.

Advantageously, a wire mesh cage is interposed between the ignition charge and the priming device and extends over the outlet vent.

In order to allow for variations in the manufacturing tolerances in the longitudinal direction of the parts of the actuator, the valve member may comprise a percussion piston slidably mounted within a bore of the valve member and rearwardly of the priming device, the piston being releasably retained within said bore by collapsible means so that upon collapse of said means, the piston can move forwardly within the valve member.

BRIEF DESCRIPTION OF THE DRAWINGS In order to make the invention more clearly understood, one embodiment thereof will now be described by way of example only with reference to the accompanying drawings in which:

FIG. 1 is an axial cross-sectional view of a pressure actuator in its inoperative position;

FIG. 2 is a view similar to FIG. il showing the actuator in its operative position; and

FIG. 3 is a bottom plan view of the actuator.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, a pressure actuator comprises a generally cylindrical housing 10 made from steel and having forward and rearward ends 11,12 respectively. The housing is bored from its forward end 11 to provide a bore 13 which reduces in diameter at a step 14 to form a bore 15. The base of the bore 15 has a shallow recess 16 in the end wall 17 of the housing to provide an annular shoulder 18 around the recess. A spigot 19 projects from the rear end of the housing and an inlet passage 20 extends through the spigot 19, through the end wall 17 and opens into the recess 16 at an inlet port 20a. Near the shoulder 14 four outlet vents 21 are provided in the wall of the housing and extend radially from the bore 15. A flange 1110 (FIG. 3) extends laterally from the rear end of the housing for mounting purposes; other mounting means can be employed if desired, for example the rearward end 12 of the housing 10 may have an external screw thread.

A cylindrical slide valve member 22 is slidably mounted within the bore 15 but in the inoperative condition of the actuator the slide valve member is retained at the rearward end of the bore and in contact with the shoulder 18 by collapsible means in the form of four shear pins 23 equi-angularly disposed around the actuator. The shear pins are disposed radially through the wall of the housing 10 and project into the slide valve member 22 so as to interconnect the housing and the valve member. The valve member has a coaxial bore 24 which opens into .a bore 25 at the rearward end, and opens into a bore 26 at the forward end to provide an annular sleeve 27. The leading end of the sleeve is internally and externally chamfered to form a circular edge 28.

A percussion piston 29 has a body portion 30 and a forwardly facing striking surface in the form of a projecting nose 31. The body portion 30 has a shorter length than that of the bore 25 and is slidably mounted in the bore 25. However, in the inoperative position of the actuator, the piston is releasably retained within the bore, with the rear face of the piston flush with the rear face of the slide valve member 22, by means of a single diametrically disposed shear pin 32 extending through the valve member and the piston.

An ignition charge container 33 is disposed within the housing 10 and comprises a cylindrical head 34 located in the bore 13 but spaced from the step 14 by a soft metallic ring 35. A body 36 of the container extends rearwardly from the head slidably within the annular sleeve 27 of the slide valve member 22, and a portion 37 of the body 36 projects rearwardly from the body to be freely relatively movable within the bore 24 of the valve member. A shoulder 38 of the body 36 surrounds the portion 37. The container is coaxially bored to provide at its forward end a recess 39 which reduces in turn to a chamber 40, a chamber 41, and a bore 42. Near the base of the chamber 40 radial holes 43 are provided in the body 36 so as to be aligned with respective vents 21 in the housing 10. Drillings 44 extend from the shoulder 38 to intersect the radial holes 43.

Within the bore 42 there is frictionally retained a percussion-operated priming device 45 of conventional design as used in the manufacture of shotgun cartridges except that the priming powder has the following composition:

Barium styphnate 10% by weight Potassium chlorate 48% Antimony sulphide 32% Lead dinitroresorcinate Tetrazene 5% A black powder igniter 48 is disposed in the chamber 41 and a thin aluminum bursting disc 49, 0.001 inches thick, rests at the base of the chamber 40 to cover the igniter 48. A two-part wire cage spacer 50 rests on the disc 49 and extends over the radial holes 43. Above the spacer 50 the lower part of a tubular charge 51 of cordite is disposed within the recess 39. The spacer 50 is not essential but it assists in retaining the disc 49 in position and in supporting the charge 51.

At the forward end of the housing an end cover 52 is secured between the forward end of the container 33 and a circlip 53 mounted in the wall of the housing 10. The end cover 52 is recessed as at 54 in order to receive the upper part of the charge 51. A stem 55 is integral with and extends forwardly from the cover 52 and has its free end screw-threaded for securing the actuator to the missile system to be actuated via suitable tubing.

An axial passage 56 extends from an outlet port 57 at the base of the recess 54 and along the stem 55.

Dust caps 58 (of which only one is shown) are fitted to close the outlet vents 21.

O-ring seals are provided on parts of the actuator as shown by the usual representation in the drawings. In use, the actuator when assembled as described above in its inoperative condition, is mounted on a rocket motor, the spigot 19 being connected to the combustion chamber of the rocket motor and the stem 55 being connected to the respective device to be actuated.

When exhaust gas at approximately 1,250 p.s.i. is injected through the inlet port a and into the recess 16, the percussion piston 29 and the slide valve member 22 are impelled forwardly as a single unit, shearing the pins 23, and move along the bore 15. During this movement, the annular sleeve 27 of the slide valve member closes the outlet vents 21 and then the circular edge 28 becomes embedded in the ring 35 to effect a gas seal therebetween. The gas pressure now exerted over the rear face of the percussion piston 29, together with the momentum of the piston, causes the pin 32 to shear thereby allowing the piston to move to the forward end of the bore (FIG. 2). The axial dimensions of the parts of the actuator are so designed that during this movement of the piston 29 relative to the valve member, the nose 3] of the piston impacts against the priming device 45 to cause ignition of the igniter 48. This, in turn, ignites the cordite charge 51 of which the pressurized gas (approximately 700 p.s.i.) thus generated passes through the outlet passage 56 to actuate the associated device. The slide valve member 22 and percussion piston 29 are held in the forward position of FIG. 2 by the approximately 1,250 p.s.i. pressure in the rear end portion of the bore 15.

By virtue of the short movement of the slide valve member 22 and piston 29 only a relatively small volume of gas is required to operate the actuator. For example, a one inch diameter slide valve member may be moved with cubic inch of gas. Furthermore, by the use of the percussion-operated priming device, a very rapid response is provided by the actuator, typically of milliseconds.

In the event of accidental ignition of the cordite charge 51 whilst the actuator is in its inoperative condition, the pressure thus generated is simply vented through the radial holes 43 and the outlet vents 21 whilst a very low ineffective pressure, of the order of 10 p.s.i., exists at the outlet end of the actuator.

I claim:

1. A pressure actuator for a missile system comprising a housing having a bore with an inlet port at a rear end thereof, an outlet port at the forward end thereof, and at least one outlet vent intermediate the inlet and outlet ports, a slide valve member slidably mounted within the bore but releasably retained adjacent the rear end of the bore by collapsible means interconnecting the housing and the valve member, the valve member having a forwardly facing striking surface and a forwardly extending sleeve portion which terminates rearwardly of the outlet vent but is adapted to close the outlet vent on forward movement of the valve member, the actuator further comprising a percussion-operated priming device mounted forwardly of, and axially aligned with, the striking surface of the valve member, and an ignition charge disposed forwardly of the priming device, the arrangement being such that upon operation of the actuator the slide valve member closes the outlet vent before the priming device is struck.

2. An actuator according to claim 1 wherein the ignition charge is spaced from the priming device and is disposed intermediate the outlet vent and the outlet port.

3. An actuator according to claim 2 wherein a wire mesh cage is interposed between the ignition charge and the priming device and extends over the outlet vent.

4. An actuator according to claim 1 and wherein the valve member comprises a percussion piston slidably mounted within a bore of the valve member and rearwardly of the priming device, the piston being releasably retained within said bore by collapsible means so that upon collapse of said means, the piston can move forwardly within the valve member. 

1. A pressure actuator for a missile system comprising a housing having a bore with an inlet port at a rear end thereof, an outlet port at the forward end thereof, and at least one outlet vent intermediate the inlet and outlet ports, a slide valve member slidably mounted within the bore but releasably retained adjacent the rear end of the bore by collapsible means interconnecting the housing and the valve member, the valve member having a forwardly facing striking surface anD a forwardly extending sleeve portion which terminates rearwardly of the outlet vent but is adapted to close the outlet vent on forward movement of the valve member, the actuator further comprising a percussion-operated priming device mounted forwardly of, and axially aligned with, the striking surface of the valve member, and an ignition charge disposed forwardly of the priming device, the arrangement being such that upon operation of the actuator the slide valve member closes the outlet vent before the priming device is struck.
 1. A pressure actuator for a missile system comprising a housing having a bore with an inlet port at a rear end thereof, an outlet port at the forward end thereof, and at least one outlet vent intermediate the inlet and outlet ports, a slide valve member slidably mounted within the bore but releasably retained adjacent the rear end of the bore by collapsible means interconnecting the housing and the valve member, the valve member having a forwardly facing striking surface anD a forwardly extending sleeve portion which terminates rearwardly of the outlet vent but is adapted to close the outlet vent on forward movement of the valve member, the actuator further comprising a percussion-operated priming device mounted forwardly of, and axially aligned with, the striking surface of the valve member, and an ignition charge disposed forwardly of the priming device, the arrangement being such that upon operation of the actuator the slide valve member closes the outlet vent before the priming device is struck.
 2. An actuator according to claim 1 wherein the ignition charge is spaced from the priming device and is disposed intermediate the outlet vent and the outlet port.
 3. An actuator according to claim 2 wherein a wire mesh cage is interposed between the ignition charge and the priming device and extends over the outlet vent. 